In September 2005, NOAA scientist Dr. Pieter Tans was asked by lab director Dr. David Hofmann to cancel a conference session on energy use and the carbon cycle due to its “policy implications”1 and was told that the words “climate change” could not appear in the titles of any presentations.2 Hoffman had previously told Tans and other NOAA scientists not to use the word “Kyoto” in presentations or papers.3

Dr. Tans, a world expert in carbon dioxide measurement and atmospheric modeling, is a chief scientist at NOAA’s Global Monitoring Division (GMD, formerly the Climate Monitoring and Diagnostics Laboratory, CMDL) in Boulder, Colorado. At the time, he was chair of the Scientific Program Committee for the Seventh International Carbon Dioxide Conference and was determined to use the conference to highlight the dominant role that carbon dioxide plays as a forcing agent in climate change.

According to documents obtained through a Freedom of Information Act (FOIA) request, and corroborated by an agency source,4 agencies that funded the conference, including CMDL, had stipulated that the topics be restricted to “carbon dioxide measurements and modeling, rather than climate change and climate modeling.”5 NOAA public affairs officers described this restriction of topic as an attempt to reduce the size of the conference, rather than censorship.

Dr. Tans’ draft abstract, which he planned to present at the conference, asserted that “CO2 is now generally recognized to be the main driver of climate change.” This text was edited down as part of the attempt to remove all mention of the words “climate change” in the titles of the poster displays and oral presentations at the conference. Dr. Hoffmann has stated that he was misinterpreted and that the specific words were not barred from presentation titles. However, Hoffmann did tell Tans that the presentations should be consistent with the topic and should not “get involved with climate change.” Tans and other presenters did not follow these restrictions.6

According to Dr. Tans, the intent of this interference only became clearer several months later, when he was told by his director—later confirmed by the deputy director—that any material dealing with climate change, including his laboratory’s website content, had to be pre-approved at the White House level.7 “It is probably for this reason that the webmaster for the conference had been ordered by the lab’s director to remove any links coupling climate change to CO2 increase,” Tans later recalled. “NOAA curtailed the ability of participants to submit material for posting on the conference website.”

Indeed, while 450 scientists convened on a subject of great contemporary importance, the conference remained largely outside of the public view. A press conference had been scheduled on the first day of the conference, but only a few local newspapers showed up. When asked about the conference, reporters from the New York Times, Washington Post, Wall Street Journal, and the BBC could not remember having been notified.8

Dr. Tans has described the negative impact of such restrictions on the credibility of government scientists, stating, “There is suspicion at the moment, and that detracts from my credibility as a scientist because people might now think, well, can we trust this guy or is he just saying things that are officially approved?”9 While Dr. Tans is comfortable ignoring agency restrictions he finds inappropriate and speaking out about interference in his scientific work, he has said in interviews that other government scientists might not feel so free. “Some people feel intimidated,” he said, “I see that.”10

1. Tans, P. 2006. Phone interview with Tarek Maassarani, March 9. To appear in a forthcoming Government Accountability Project report on Political Interference in Climate Change Science, March 2007.

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